Electrophotographic photoreceptor, and image forming apparatus and process cartridge using the electrophotographic photoreceptor

Abstract

An electrophotographic photoreceptor is provided, including an electroconductive substrate and a photosensitive layer located overlying the electroconductive substrate, wherein an outermost layer of the electrophotographic photoreceptor includes a resin including a graft copolymer in which a monomer having a polar group is graft polymerized to a polycarbonate resin, a polyarylate resin, or a copolymer thereof, and a filler; along with an image forming apparatus and a process cartridge using the electrophotographic photoreceptor.

1. An electrophotographic photoreceptor, comprising:
 an electroconductive substrate; and 
 a photosensitive layer located overlying the electroconductive substrate, wherein an outermost layer of the electrophotographic photoreceptor comprises: 
 a resin comprising a graft copolymer in which a monomer having a polar group is graft polymerized to a polycarbonate resin, a polyarylate resin or a copolymer thereof; wherein the monomer having a polar group is selected from acrylic acid or vinylpyridine; and 
 a filler; 
 wherein the polycarbonate resin, polyarylate resin or copolymer thereof is a resin consisting of units of bisphenol compounds having the following formula (1) optionally having an alkyl group:
   HO—X—OH  (1)
 
 
 
       wherein X represents a divalent group having the following formulae (2) or (3): 
       
         
           
           
               
               
           
         
       
       wherein each of R 101 , R 102 , R 103 , and R 104  independently represents a halogen atom, an unsubstituted alkyl group having 1 to 6 carbon atoms, or an unsubstituted aryl group; each of o and p independently represents an integer of 0 to 4; each of q and r independently represents an integer of 0 to 3; Y represents a single bond, a linear alkylene group having 2 to 4 carbon atoms, —O—, —S—, or a functional group selected from groups having formulae (4) to (7): 
       
         
           
           
               
               
           
         
       
       wherein R 105  represents a halogen atom, an unsubstituted alkyl group or alkoxy group having 1 to 6 carbon atoms, or an unsubstituted aryl group; s represents an integer of 0 to 4 and t represents a positive integer; 
       
         
           
           
               
               
           
         
       
       wherein each of R 106  and R 107  independently represents a hydrogen atom, a halogen atom, an unsubstituted alkyl group or alkoxy group having 1 to 6 carbon atoms, or an unsubstituted aryl group, wherein R 106  and R 107  optionally share bond connectivity to form a carbon ring having 5 to 12 carbon atoms; 
       
         
           
           
               
               
           
         
       
       wherein each of R 108 , R 109 , R 110 , and R 111  independently represents a hydrogen atom, a halogen atom, an unsubstituted alkyl group or alkoxy group having 1 to 6 carbon atoms, or an unsubstituted aryl group; and 
       
         
           
           
               
               
           
         
       
     
     
       2. The electrophotographic photoreceptor according to  claim 1 , further comprising a protective layer located overlying the photosensitive layer. 
     
     
       3. The electrophotographic photoreceptor according to  claim 2 , wherein the protective layer and the photosensitive layer have a continuous structure, and wherein the protective layer satisfies the following relationship:
   σ≦ D/ 5
 
 
       wherein D represents an average of maximum thicknesses of the protective layer in units of micrometers in 20 segments of 5 μm wide when a portion of a cross section of the photoreceptor of 100 μm wide is divided into 20 segments, and σ represents a standard deviation of the 20 maximum thicknesses. 
     
     
       4. The electrophotographic photoreceptor according to  claim 3 , wherein the protective layer satisfies the following relationship:
   σ≦ D/ 7.
 
 
     
     
       5. The electrophotographic photoreceptor according to  claim 1 , wherein the filler comprises an inorganic filler. 
     
     
       6. The electrophotographic photoreceptor according to  claim 5 , wherein the inorganic filler comprises silica or a metal oxide. 
     
     
       7. The electrophotographic photoreceptor according to  claim 6 , wherein the inorganic filler is the metal oxide and the metal oxide comprises a material selected from the group consisting of titanium oxide and aluminum oxide. 
     
     
       8. An image forming apparatus, comprising:
 a photoreceptor; 
 a charger configured to charge the photoreceptor; 
 an image irradiator configured to irradiate the photoreceptor with a light beam to form an electrostatic latent image on the photoreceptor; 
 an image developer configured to develop the electrostatic latent image with a toner to form a toner image on the photoreceptor; and 
 a transfer belt configured to transfer the toner image onto a receiving material optionally via an intermediate transfer medium, 
 wherein the photoreceptor is the electrophotographic photoreceptor according to  claim 1 . 
 
     
     
       9. The image forming apparatus according to  claim 8 , wherein the electrophotographic photoreceptor further comprises a protective layer located overlying the photosensitive layer. 
     
     
       10. The image forming apparatus according to  claim 9 , wherein the protective layer and the photosensitive layer have a continuous structure, and wherein the protective layer satisfies the following relationship:
   σ≦ D/ 5
 
 
       wherein D represents an average of maximum thicknesses of the protective layer in units of micrometers in 20 segments of 5 μm wide when a portion of a cross section of the photoreceptor of 100 μm wide is divided into 20 segments, and a represents a standard deviation of the 20 maximum thicknesses. 
     
     
       11. The image forming apparatus according to  claim 10 , wherein the protective layer satisfies the following relationship:
   σ≦ D/ 7.
 
 
     
     
       12. A process cartridge for an image forming apparatus, comprising:
 the electrophotographic photoreceptor according to  claim 1 ; 
 a housing containing the electrophotographic photoreceptor; and 
 optionally, one or more members selected from the group consisting of a charger, an image irradiator, an image developer, an image transferrer, a cleaner and a discharger. 
 
     
     
       13. The process cartridge for an image forming apparatus according to  claim 12 , wherein the electrophotographic photoreceptor further comprises a protective layer located overlying the photosensitive layer. 
     
     
       14. The process cartridge for an image forming apparatus according to  claim 13 , wherein the protective layer and the photosensitive layer have a continuous structure, and wherein the protective layer satisfies the following relationship:
   σ≦ D/ 5
 
 
       wherein D represents an average of maximum thicknesses of the protective layer in units of micrometers in 20 segments of 5 μm wide when a portion of a cross section of the photoreceptor of 100 μm wide is divided into 20 segments, and σ represents a standard deviation of the 20 maximum thicknesses. 
     
     
       15. The process cartridge for an image forming apparatus according to  claim 14 , wherein the protective layer satisfies the following relationship:
   σ≦ D/ 7.
 
 
     
     
       16. The electrophotographic photoconductor as claimed in  claim 1 , wherein the resin is a member selected from the group consisting of vinylpyridine graft bisphenol Z-form polycarbonate, acrylic acid graft bisphenol Z-form polycarbonate, vinylpyridine graft bisphenol Z-form polyarylate, acrylic acid graft bisphenol Z-form polyarylate, vinylpyridine graft bisphenol E-form polycarbonate, and acrylic acid graft tetrabromobisphenol A-form/bisphenol Z-form polycarbonate copolymer.